Thermostat



Nov. 12, 1929. A. E. ELLIS 1,735,269

THERMOSTAT Filed Feb. 16, 1925 Imke/ni@ Patented Nov. 12, 1929 UNITED STATES PATENT ol-FICE .AXEL E. ELLIS,OF LONG ISLAND CITY, NEW YORK, ABSIGNOR T W. BARBER, HORACE D. EVEBETT, AND GEORGE SIEGEL, TBUSTEEB, IN SAIAS MANUFACTURING OOIPANY THERMOSTAT application mea rem-nary 1s, 192e. smal 1r. sans.

This invention relates to that class of thermostats particularly designed for use in connection with {lat-irons, and ithas for its object the construction of a simple and eifective means for switching off the current whenever "15 away, she thinks she will be gone but a moment and therefore fails to switch oi the current. After the lapse of an unexpectedly long time she returns to her work, and, while there may have been no conflagration result- 2o ing from overheating, as in those irons with no thermostat at all, yet there has occurred a bad waste of electricity to pay for, and, in

addition, a needless inju to the device owing to the largel number oA arcings as the cur- 25 rent is turled olf and on.

In the drawings forming part of this specication, Fig. 1 is a plan view of the thermostat box. Fig. 2 is a perspective view of the complete iatiron. Fig. 3 is a perspective diagram showing the wiring. Fig. 4 is a detail view of the dog. Fig. 5 is a perspective view of the movable terminal. Fig. 6 is a cross section of the latiron and thermostat-box.

Thecase containing this thermostat is in the operating parts, and the section 2 being in effect the cover having anges 3 fittingdown about the section 1. The section or box 1 has iixed in one end an elongated block 4 of insulating material holding two vertically desoending pins 5 each secured therein and 'put into circuit with terminals 6 by small `screws 7. One of these terminals carries an arched contact member 9 preferably composed of spring brass normally out of contact with the other terminal, but capable of being pressed into such contact, the foot 10 which performs the contacting being preferably split into a plurality of toes. l. Spaced from the contact 9 is a dog 11 pivottwo sections 1 and 2, the section 1 containing ally supported at 12 and bearing a small block 13 of non-conducting material disposed to meet thearch of the contact 9 when the latter is in the position shown in Fig. 1 and to press the foot 10 against the terminal thereat. The dog 11 is formed with a lip 14 designed to be enga ed by the end of a two-metal arm15 and there y to continue the engagement of the foot 10 and the terminal: The opposite end of the arm is bent at right angles tothe arm, and this elbow 16 is fastened to the adjacent end wall of the box 1. A cam-pin 17 suit-ably supported enables the arm 15 to be adjusted relative to the dog 11. When the arm 15 receives the degree of heat which the iron is designed to have, the arm curves away from the lip 14 and releases the dogll therefrom, permitting the spring contact 9. to sway away from the terminal with which it had been in touch. 7 0

For resetting the dog and contact, a thumbpiece 20 located on the outside of the cover 2 has a spindle 21 rigid therewith and reaching through into the interior of the box 1, where it is provided with a diametrically disposed 76 pin 22 which by its bringing up against the adjacent walls of the boxlimits the movements of the linger-piece.

When the finger-piece 20 is swung over toward the left hand as-viewed in Fig. 1, an end of the pin 22 comes against the lug 23 connectedwith the dog 11 and presses the latter against'the push of the contact 9 until the co-acting terminal 6 is reached and the bimetal arm 15 snaps in behind the lip 14. I prefer to have the lug 23 pivoted upon the same pivot screw 12 as is the dog and between the outer and inner sections of the latter. This lug is preferably made U-shape in cross section, and between its two parts and upon the pin or screw 12 is mounted a slender helical spring 24 so disposed as normally to sustain the lug' at an intermediate position. This position is for the purpose of reventing the end ofthe pin 22 from stri 'ng the tip ofthe lug 23 after having passed 1t in moving the dog 11 to its illustrated position and then returning to its normal position. The lug 23 is'pivoted to swing freely toward the right to permit the pin 22 to pass on its 10 return to normal, being urged thereto by the helical spring A24 located on the spindle 21.

The pressure against the lug 23 which acts to set the dog 11 is communicated to the latter by the shoulder 25 of the dog. The dog is formed with a tail 26 which coacts with a linger 27 bent out from a side wall of the box to limit the throw of the dog under the im'- pulse of the spring contact 9.

As illustrated in Fig. 3, the two pins 5 enter sockets 30 within the flat-iron, one socket being wired to a pin 31 of the iron, and the other to one terminal of the heater element, whereby the current communicated in a well known manner to the pins 31 is diverted to the thermostat.

Electric fiatirons are usually made up of a base 36 having a recess containing the heating element 36a consisting of high-resistance coils suitably insulated from the metal; a block 36b of cast'iron to give weight and to store up heat, and a head 37, a sheet of asbestos 37a being introduced between the block 36b and the head 37 for protecting the operators hand from' the heat. This has thc effect of delaying the transmission'of heat to the thermostat; and hence, when the iron is cold and the current is first turned on, it takes considerable time for the heat to reach and operate the thermostat, while the base gets hot very quickly and may scorch any clothing upon which it may be resting. To obviate this, I connect the ,heating element to the thermostat directly through metal of hi h heat conductivity, as copper. To this en I rivet a strip of copper 35 to the undersurface of the box 1 close beneath the thermostatic spring 15, thick enough to Contact with vthe head 37. Just beneath this element 35 I locate against the inner surface of the head 37 a similar strip of copper 37 b which is supported by a short rod 37c preferably riveted thereto and passed through a hole in the block 36b and the asbestos sheet 37 into close proximity to the heating element.

For enabling the operator to see whether or not the current 4is on, the cover 2 is formed with a hole 39 directly over the dog 11 which is provided with a spot 41 preferably red in color disposed to come beneath the hole 39 when the dog is holding the movable terminal in circuit. When this spot is not. visible it shows that the current is cut out.

' Another important feature not above mentioned is that of having the length of the E1n 22 andthe stop-shoulder 25 so disposed t at the dog -11 is pressed against the movable terminal 9 more than enough to permit the heat-controlled arm 15 to swing 1n beneath the lip 14, and also more than merely to put the foot 10 of the part 9 into touch with the terminalv 6. The result of this is to cause the foot 10 to slide along the terminal 6 twice and thereby to ensure perfectelectric contact therewith. This second slide is, of course,

due to the retreat of the dog 11 as it moves back into engagement with the arm 15.

As shown in Fig. 1, the arm 15 is providedl with a hardened steel tip 43 suitably attached thereto to ensure against Wear; the dog 11 being likewise of steel stamped and bent into the form illustrated and hardened in the vicinity of its lip 14.

The foot 10 of the terminal 9 is not only split into a plurality of toes, as shown in Fig. 5, to ensure full Contact with the terminal 6, but I find it a most important thing to separate them. Vhile milling these toes by means of a thin cutting disk will accomplish this, it is far more economical to split the leaf spring thereat. Inasmuch as this will leave the toes more or less in contact, I find it essential to give a blow or two with a prick-punch or the like at the bases 44 of these toes, and thereby to properly separate them. It has been the failure to do this in previous contact members which has led to the discouraging results hitherto met with.

As shown in Fig. 3, the notches 38 which enclose the strap 40 are formed with spurs 41 which are bent in beneath the edges of the strap for locking the thermostat in place upon the tlatiron.

What I claim as my invention is:

1. A thermostat comprising a stat1onary terminal, a leaf spring terminal conned at one end and adapted to have its other end brought into contact with the stationary terminal, a pivotally supported dog adapted.

when swung in one direction to press against an intermediate section of the leaf sprin to bring the terminals into contact, and a t e r mostaticall controlled device for holding sald doghin saidy position.

2. A thermostat comprising a stat1onary terminal, a leaf spring terminal confined at one end, a pivotally supported dog adapted to be pressed against an intermediate portlon of said leaf spring but insulated therefrom for putting its free end into engagement with the stationary terminal, and a thermostatically controlled device holding said arm in said position.

3. A thermostat comprlsing a .stationary terminal, a movable terminal, a pivoted dog insulated from the latter for pressing the movable terminal into engagement with the stationary terminal, a swinging finger-piece for forcibly swinging said dog, and means whereby a movement of said finger-piece 1n one d1- rection will move said dog into its pres'smg action, and a movement in the opposite dlrection will not affect the dog.

4. In a thermostat, a stationary terminal, a movable terminal, a pivoted dog insulated from the latter forputting the terminals into contact, a lug pivoted to said dog, a spring yieldingly holding the lug in operative p os1- \tion, a spindle having means for its forcible rotation through a limited arc, and a pin radially projecting from said spindle adapted to engage said lug for actuating said dog.

5. In a thermostat, a stationary terminal, ar movable terminal, a pivoted dog insulated from the latter for pressing the terminals into Contact, a lug pivotedf to said dog to swinof through a limited relative arc, a spring yield ingly holding said lugintermedlate of said are, a spindle having means for its forcible actuation, and a pin radially projecting from said spindle for engagement with sald lug.

In testimony that I claim the foregoing invention, I have hereunto Set my hand this third day of February, 1926. l

AXEL E." ELLIS. 

